Engines may use various forms of fuel delivery to provide a desired amount of fuel for combustion in each cylinder. One type of fuel delivery uses a port injector for each cylinder to deliver fuel to respective cylinders. Still another type of fuel delivery uses a direct injector for each cylinder.
Engines have also been described using more than one injector to provide fuel to different fuel blends to the engine. For example, the papers titled “Calculations of Knock Suppression in Highly Turbocharged Gasoline/Ethanol Engines Using Direct Ethanol Injection” and “Direct Injection Ethanol Boosted Gasoline Engine: Biofuel Leveraging for Cost Effective Reduction of Oil Dependence and CO2 Emissions” by Heywood et al. describe directly injecting ethanol to improve charge cooling effects, with port-delivered gasoline.
However, the inventors herein have recognized several issues with such systems. Specifically, if any separate storage is used to maintain the ethanol separate from gasoline, this may create issues with regard to fuel vapor purging of generated vapors. For example, one fuel may generate more or less vapors than the other fuel. Further, fuel vapors from one fuel may migrate to the storage location of the other fuel. Further still, such systems may have increased cost due to the additional storage requirements.
Thus, in one approach a method for managing vapors generated by a first and second reservoir onboard a vehicle traveling on the road is provided. The method comprises inducting vapors from the first and second reservoirs during engine operation; and reducing flow of vapors from first the reservoir to second reservoir and from the second reservoir to the first reservoir.
In this way, it is possible to maintain both reservoirs with the appropriate fuel type, while being able to purge vapors from both reservoirs to the engine intake manifold. Further, it is possible to reduce contamination between the reservoirs.
In another approach, a system for an engine of a vehicle traveling on the road is provided, the system comprising: a first fuel reservoir configured to store a first fuel separate from said second fuel; a second fuel reservoir configured to store said second fuel; a first canister coupled to at least one of said first and second reservoir; a fuel vapor purge valve coupled to an intake manifold of the engine configured to vary an amount of purge vapors from said first and second fuel tank inducted into the intake manifold in response to operating conditions.
In this way, can purge vapors from both reservoirs through at least one common control valve, thereby reducing cost.